docs: def dedupe_and_sort(sequence, first=None, last=None):
      """
      De-dupe and partially sort a sequence.
  
      The `first` argument should contain all the items that might appear in
      `sequence` and for which the order (relative to each other) is important.
  
      The `last` argument is the same, but matching items will be placed at the
      end of the sequence.
  
      For example, `INSTALLED_APPS` and `MIDDLEWARE_CLASSES` settings.
  
      Items from `first` will only be included if they also appear in `sequence`.
  
      Items from `sequence` that don't appear in `first` will come
      after any that do, and retain their existing order.
  
      Returns a sequence of the same type as given.
      """
      first = first or []
      last = last or []
      # Add items that should be sorted first.
      new_sequence = [i for i in first if i in sequence]
      # Add remaining items in their current order, ignoring duplicates and items
      # that should be sorted last.
      for item in sequence:
          if item not in new_sequence and item not in last:
              new_sequence.append(item)
      # Add items that should be sorted last.
      new_sequence.extend([i for i in last if i in sequence])
      # Return a sequence of the same type as given.
      return type(sequence)(new_sequence)